Magnetron sputtering apparatus with an integral cooling and pressure relieving cathode

ABSTRACT

A sputtering apparatus includes a sputtering process chamber, a sputtering target assembly, and an adjustable magnetron assembly. The sputtering target assembly includes heating/cooling passages within the sputtering target assembly. A first side of a heat exchanger/pressure relieving plate is attached to a target backing. A second or opposing side of the heat exchanger/pressure relieving plate is attached to an insulation cover to form, within the sputtering target assembly, pressure relieving vacuum passages. The target assembly completely covers and seals against a high-vacuum-compatible insulator resting over and sealed to a top flange of the process chamber. A magnetron assembly resting over the target assembly, is independent from vacuum, or vacuum components, and provides means to move or scan a magnetron or magnet array over the target assembly. The distance between the magnetron and target assembly is adjustable throughout the useful life of the target independent from vacuum, or vacuum components.

FIELD OF THE INVENTION

This invention relates to a magnetron sputtering apparatus employing athin integral cooling and pressure relieving sputtering cathode, and anadjustable magnetron drive mechanism that allows for plasma/erosionpattern optimization throughout the useful life of the target.

BACKGROUND OF THE INVENTION

One of the most important commercial processes for depositing thin filmsof a desired material onto a substrate is sputter deposition, also knownas sputter coating or sputtering. Sputter deposition is used extensivelyin many industries including the microelectronics, data storage anddisplay industries to name but a few.

Generally, the term sputtering refers to an “atomistic” process in whichneutral, or charged, particles (atoms or molecules) are ejected from thesurface of a target material through bombardment with energeticparticles. A portion of the sputtered particles condenses onto asubstrate to form a thin film. The science and technology of sputteringis well known and described for example in Vossen, J. L., Kern, W., ThinFilm Processes, Academic Press (1978). Sputtering can be achievedthrough several techniques. Generally, in “cathodic” (“diode”)sputtering the target is at a high negative potential relative to othercomponents, usually through application of a negative bias from a powersupply, in a vacuum chamber system, typically containing an inert gas ormixture of gases at low pressure. A plasma containing ionized gasparticles is established close to the target surface and ionized gasparticles are accelerated by the action of the electric field towardsthe target surface. The bombarding particles lose kinetic energy throughmomentum exchange processes with the target atoms, some of the latterparticles gain sufficient “reverse” momentum to escape the body of thetarget, to become sputtered target particles. Note a sputtered particlemay be an atom, atom cluster or molecule either in an electricallyneutral or charged state. A flux of sputtered particles may contain anyone or any mixture of such entities.

Coating high aspect ratio structures is of critical importance, e.g., inemerging submicron semiconductor interconnect metalization and highdensity data storage media applications. In such cases the bounds ofapplication of magnetron sputter deposition is approaching its limit.For example, in coating via type structures in microelectronicsinterconnect applications, it is well known that sputter depositionsuffers from film buildout at the upper edges of the via resulting in atrapped void, “keyhole” type film defect as well as other film defects.See, for example, Rossnagel, S., J.Vac. Sci. Tech.B., Vol.16, No.5, p.2585 (1998). This effect is exasperated with reducing dimensionality andincreased aspect ratio. Proponents of current commercial PVD processesassert they can confornally cover relatively high aspect ratio features,or fill relatively high aspect ratio channels or vias, having a criticaldimension of at least 0.18 micron, or perhaps greater than 0.13 micron.

Several sputter PVD techniques, many of them developed commerciallyrelatively recently, attempt to control the directionality of theincident sputtered particle flux at a substrate e.g., physicalcollimation techniques, hollow cathode sputtering, arc sputtering, selfionized sputtering, ionized physical vapor deposition (IPVD) and longthrow methods. The latter two techniques probably represent state of theart commercial technologies. The scope, scalability, efficiency and costconsiderations of directional sputter technologies have been reviewed byRossnagel, S., J.Vac. Sci. Tech.B., Vol.16, No.5, p. 2585 (1998). Thebest techniques utilize tooling and/or process attributes to achieve adegree of control over the angular distribution of incident sputteredparticles. These methods are in fact expressly designed to overcome whatare believed to be inherent deficiencies in basic magnetron cathodesputter deposition characteristics and target materials design whichlimit control of the substrate incident angular sputtered fluxdistribution.

U.S. Pat. No. 5,948,215; U.S. Pat. No. 5,178,739; and Patent CooperationTreaty published application No. WO 98/48444 disclose ionized plasmavapor deposition processes, and are incorporated herein by reference.

Long throw methods utilize ballistic (i.e., collisionless) transport anda long throw path to the substrate to “optically” filter the magnetroncathode emitted flux such that only relatively low angle components ofthe emitted flux (i.e., those close to the target normal) are incidentat the substrate. The long throw process is clearly inefficient throughflux dilution and suffers from inherent asymmetries in the incidentflux. See Rossnagel, S., J. Vac. Sci. Tech. B., Vol.16, No.5, p. 2585(1998).

Planar Magnetron Sputtering apparatuses are well known Physical VaporDeposition (PVD) tools commonly used in, for example, the semiconductorindustry for the deposition of thin films of metals such as aluminum andits alloys, refractory metals, and ceramics onto a substrate; forexample, a silicon wafer or glass sheet being processed. In general, theprocess of Planar Magnetron Sputtering involves creating and confining aplasma of ionized inert gas over the consumable surface of an energizedCathode Assembly in order to dislodge, by momentum transfer, atoms ormolecules from the consumable surface. The consumable surface of acathode assembly consists of the material to be sputtered and iscommonly called a sputter “target” in Industry. The target is placed arelatively short distance from the substrate in order to improvecollection of the ejected target atoms onto the substrate.

Initially, a discharge caused by primarily electrons emitted from thesurface of the target, produced by gas ion bombardment of the targetresulting from ionization of the gas by natural background ionizingradiation, strike or ignite the plasma. The target is energized by anapplied electric field (DC, RF, or both) in an evacuated chamber that isbackfilled with an inert gas to typically the 10⁻⁴-10⁻¹ millitorrpressure range. Then, both electrons emitted by the target surface andelectrons created by ionizing impacts with the inert gas will beconfined near the target surface by means of the magnetron's magneticfield; which is applied crosswise to the electric field. The createdions accelerate towards the surface of the target and dislodge atoms ormolecules from it; many of these atoms or molecules will be directedtowards the substrate creating a thin film onto the substrate.

It is well known, that maximum erosion of a target occurs where lines ofmagnetic flux are parallel to the consumable surface of the target. Toincrease the sputter-deposition rate for a given applied electric fieldto the cathode, the magnetron should also ride as close as possible tothe side opposite to the consumable surface of the target such that theintensity of the parallel component of magnetic field lines above thetarget is maximized. Therefore, a design goal is to design a targetassembly with as thin a cross-section as possible.

In addition, film-properties, for example uniformity on the substrate,depend greatly on the uniformity of erosion of the target; therefore,other design goals are to design a magnetron that can produce a uniformplasma intensity, and design a drive mechanism that can sweep themagnetron uniformly over the entire target surface.

As the magnetron is swept over the target, considerable energy isdissipated in the form of heat by the ions striking the surface of thetarget; therefore, the target must be cooled in order to avoid meltingthe cathode assembly or damaging the equipment. The target in thecathode assembly is normally mounted over a backing plate and coolingmeans provided to it.

The target assembly in a magnetron sputtering device is generally placedover a sputtering opening of a process chamber to seal the processchamber such that it can be evacuated and then maintained at the lowpressures required for the sputter process. The large forces acting onthe target assembly due to the pressure differential between ambientatmospheric pressure and the vacuum inside the process chamber requirethat the target assembly, in particular the backing plate, be designedof considerable thickness to overcome the resultant bending forces.Earlier prior art cathodes were also designed to overcome the bendingforces produced by coolants impinging onto the backing plate.

As demand for processing larger substrates continues, and the size ofthe cathode assembly is scaled accordingly, prior art solved the targetassembly bending problems associated with coolants impinging on one sideof the backing plate by fitting the target assembly with internalcooling channels.

More recently, prior art has solved the target assembly pressuredifferential problems associated with applying vacuum from only theprocess chamber side by evacuating the magnetron housing enclosure whichis normally mounted over the target assembly.

FIG. 1 is a simple representation of a sputtering device, shown in U.S.Pat. No. 5,433,835, showing a processing chamber 1 that encloses asubstrate 5 to be sputter coated. The substrate 5 is surrounded by adark space or deposition shield 4 to prevent deposition of material frombeyond the edge of the target. A lower insulating ring 2 rests on thetop flange of the processing chamber 1. A laminated target assembly 8is-located on the lower insulating ring 2. Inlet and outlet coolinglines 3,9 provide coolant to the internal cooling channels of targetassembly 8. An upper insulating ring 7 insulates the top chamber 6 fromthe target assembly 8. Top chamber 6 is evacuated to equalize the vacuumforces exerted on target assembly 8 by processing chamber 1.

The above mentioned reference, and related U.S. Pat. Nos. 5,487,822(Jan. 30, 1996), U.S. Pat. No. 5,565,071 (Oct. 15, 1996), U.S. Pat. No.5,595,337 (Jan. 21, 1997), U.S. Pat. No. 5,603,816 (Feb. 18, 1997), U.S.Pat. No. 5,676,803 (Oct. 14, 1997), U.S. Pat. No. 5,799,860 (Sep. 1,1998) solved cooling and pressure differential problems by providinginternal cooling channels to the target assembly 8 and fitting a topvacuum chamber 6 over it to essentially equalize the forces imparted bythe process vacuum chamber 1; however, the techniques employedintroduced several disadvantages.

Main disadvantages are:

The top chamber 6 has to be designed rigid enough to overcome the vacuumforces; therefore introducing design complexity and cost,

The magnetron drive (not shown in FIG. 1) resides inside the top chamber6; therefore, several vacuum seals must be provided to couple the drivecomponents inside the top chamber 6 to the external components thatenergize them.

Any maintenance or service to the magnetron-drive mechanism, enclosed bytop chamber 6, requires that the whole system be brought to atmospherein order to avoid bending the now thinly designed target assembly;resulting in increased downtime for the tool.

In order to reduce costs, the same pump is generally used to evacuate orrough both the process vacuum chamber 1 and the top chamber 6. In suchcase, lubrication to the magnetron drive inside the top chamber 6 needsto be vacuum compatible in order to avoid contaminating the rough pumpand high-vacuum components. Vacuum-compatible lubricants are generallymore expensive and their lubricating properties normally inferior tostandard lubricants.

FIG. 2 shows a detail cross-sectional view of an embodiment of U.S. Pat.No. 5,876,573, a more recent prior art design-variation that alsoaddresses the problems of cooling and pressure differential associatedwith large target assemblies that seal to the opening of a processchamber; however, at the expense of yet considerable design complexity,as will be explained shortly.

According to this embodiment, a magnetron sputtering system 10 is usedto perform sputtering of a target material from a target onto asubstrate. The target 16 is mounted to a backing plate 18 that includesseveral internal cooling conduits 19, the assembly is positioned withina vacuum (processing) chamber 11 defined by chamber walls 39, and heldin place by retainer ring 13 which is coupled to bearing support 36. Acoolant manifold 12 connects to cooling conduits 19 on the backing plate18, and to several conduit tubes 40 attached to coolant manifold 12. Theconduit tubes 40; which also energize the backing plate 18 and target16, extend through magnetron assembly housing 21, third insulator ring35, and bearing support 36 as shown in FIG. 2.

Insulating jacket 34 electrically insulates conduit 40 from magnetronassembly housing 21. A magnet array 15 is positioned above backing plate18, and enclosed by magnetron assembly housing 21, which provides ahousing for the entire magnetron assembly 24, and sits on top of chamber11.

The magnetron assembly housing 21 is formed to enclose the magnet array15 and form a space, on the magnet array chamber 22, within themagnetron assembly housing 21. Magnet array chamber 22 comprises a spacewithin magnetron assembly 24 that lies above backing plate 18. Inoperation, the pressure within the magnet array chamber 22 can bereduced to a pressure much lower than atmospheric by operating a pumpthrough pump port 20 that connects to magnet array chamber 22.

U.S. Pat. No. 5,876,573 seems to retain all of the above-mentioneddisadvantages of U.S. Pat. No. 5,433,835; that is:

The magnetron assembly housing 21 has to be designed to withstand thevacuum forces,

Driving the magnet array 22 requires vacuum seals to couple to the motor38, e.g. ferrofluidic feed-thru 27, etc.

Any service to components enclosed by magnetron assembly housing 21require that the whole system be brought to atmosphere in order to avoidbending the now thinly designed backing plate 18.

Lubricants used (to extend the life of the bearing) with the KAYDON(Kaydon Corp., Muskegon, Mich.) bearing enclosed by magnetron assemblyhousing 21 should be vacuum compatible if the pump port 20 is incommunication with the (processing) chamber 11; else, an additional pumpshould be dedicated to evacuate the magnet array chamber 22.

Energized conduit tubes 40 extending through magnetron assembly housing21, third insulator ring 35, bearing support 36, and mating with coolantmanifold 12 need to be kept at atmosphere, as shown by the enclosingsealing devices. These additional sealing devices are required to avoidarcing or glow discharging from the energized conduit tubes 40; whichwould be the case if conduit tubes 40 were to be exposed to theevacuated magnet array chamber 22.

Additionally, as it has been shown without electrical insulation in U.S.Pat. No. 5,876,573, the exposed to vacuum surfaces of a once energizedbacking plate 18 within magnet array chamber 22 would very likely eitherarc to the magnet array 15 or produce a parasitic glow discharge in theevacuated magnet array chamber 22.

The disadvantages of the existing sputtering target systems as describedabove continue to inhibit the wide use of sputtering as an efficient andcost-effective means for applying surface coatings, particularly tolarge area substrates.

SUMMARY OF THE INVENTION

This invention relates to an improved configuration for a highproductivity sputtering device including a target or cathode assemblywhich has a thin integral cooling and pressure relieving structure, andan adjustable magnetron drive mechanism that can be maintained orserviced without affecting the vacuum components, or the vacuumintegrity within the target assembly and process chamber. Thisconfiguration overcomes many of the drawbacks of the previousconfigurations and provides a structure and method to improve sputteringcoverage of large-area substrates.

In particular, the present invention provides a sputtering apparatuscomprising a sputtering target assembly comprising:

a sputtering target and target backing plate assembly having opposedfirst and second sides, the first side providing material forsputtering,

a pressure relief plate having opposed first and second sides, thetarget and target backing plate assembly second side being in contactwith the first side of the pressure relief plate;

heat exchange passages selected from at least one member of the groupconsisting of:

heat exchange passages defined between the opposed sides of thesputtering target and backing plate assembly or between the opposedsides of the pressure relief plate, and

heat exchange passages defined by heat exchange cavities formed in atleast one member of the group consisting of the first side of thepressure relief plate and the second side of the target and targetbacking plate assembly, wherein the heat exchange passages are formedbetween the first side of the pressure relief plate and the second sideof the target and target backing plate assembly which enclose the heatexchange cavities,

the heat exchange passages having one or more inlet and outlet openings;

an insulation cover unit having opposed first and second sides;

wherein the second side of the pressure relief plate is in contact withthe first side of the insulation cover unit to form a vacuum pressurespace therebetween capable of maintaining a vacuum therein and thevacuum pressure space has one or more vacuum ports.

Typically, the heat exchange passages are defined by having heatexchange cavities formed in the first side of the pressure relief platesuch that, when the first side of the pressure relief plate is contactedto the second side of the target and target backing plate assembly, theheat exchange passages are formed between the heat exchange cavities inthe pressure relief plate and the target and target backing plateassembly enclosing those heat exchange cavities, and/or the heatexchange passages are defined by having heat exchange cavities formed inthe second side of the target and target backing plate assembly suchthat, when the first side of the pressure relief plate is contacted tothe second side of the target and target backing plate assembly, theheat exchange passages are formed between the heat exchange cavities inthe target and target backing plate assembly and the pressure reliefplate enclosing those heat exchange cavities.

There is contact of opposed sides of the target and target backing plateassembly and the pressure relief plate in excess of contact ofperipheral areas of the target and target backing plate assembly and thepressure relief plate. There is also contact of opposed sides of thepressure relieving plate assembly and the insulation cover in excess ofcontact of peripheral areas of the target and pressure relieving plateassembly and the insulation cover. This contact in the non-peripheral(e.g., central) portions of these opposed sides bordered within therespective peripheral areas can be achieved by these sides havingfins/walls extending from the respective sides to contact opposedfin/wall surface or other surface area of the respective opposed side.These contacts in these nonperipheral portions help the target assemblyto withstand pressure forces upon or within it.

For example, one embodiment of the sputtering apparatus of the presentinvention primarily comprises a sputtering process chamber, a sputteringtarget assembly, an adjustable magnetron assembly, and provides asputtering target assembly with integral heating/cooling and pressurerelieving passages. A series of cavities/grooves and fins/walls areconstructed on both sides of a heat exchanger/pressure relieving platewithin the sputtering target assembly. A first side of the heatexchanger/pressure relieving plate is attached to a target backing plateto form heating/cooling passages within the sputtering target assembly.A second or opposing side of the heat exchanger/pressure relieving plateis attached to an insulation cover to form, within the sputtering targetassembly, pressure relieving passages with the sputtering processchamber. The target assembly completely covers and seals against ahigh-vacuum-compatible insulator resting over and sealed to the topflange of the sputtering processing chamber. A magnetron assembly, e.g.,a planar magnetron. assembly, resting over the target assembly, isindependent from vacuum, or vacuum components, and provides means tomove or scan about a magnetron or magnet array over the target assembly.

The distance between the magnetron and the target assembly can beadjusted throughout the useful life of the target independent fromvacuum, or vacuum components. Depending upon the use, it may bedesirable for the magnetron or magnet array to produce an intense,narrow plasma field for an improved target erosion pattern. However,such intense, narrow plasma fields are not necessary, and depending uponthe use might not be desired. An insulating sleeve that also centers thetarget assembly to the sputtering process chamber protects the perimeterof the energized target assembly. In this way large substrates can besputtered effectively and uniformly without adverse sputtering effectsdue to target deflection and cooling deficiencies, and without affectingthe vacuum integrity in the sputtering process chamber due to servicerequirements to the magnetron assembly.

These sputtering assemblies may be employed in magnetron sputteringgenerally. In some instances they may assist to achieve directionalemission characteristics which can be maintained through ballistictransport of the emitted particles and simple geometric considerations,which promote a high degree of directionality to the substrate incidentsputtered particle flux. Directional emission refers to an angulardistribution of as-emitted sputtered particles whose flux intensity ischaracterized by a distribution of particles in which the majority ofemitted particle flux is contained within a narrow peak, or peaks,superimposed upon a low level background angular distribution. Ideally,the directionally emitted material arrives at the substrate at about thesame one or few narrow ranges of angles most characteristic of emissionfrom the target material. This makes it much easier to uniformly coathigh aspect ratio features on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simple representation of a sputtering device shown in priorart, a planar magnetron sputtering device, comprised primarily of atarget assembly with internal cooling passages and a pressure-relievingtop chamber, is generally placed over a sputtering opening of asputtering chamber to seal the chamber. The forces acting on the targetassembly due to vacuum in the process chamber are equalized, or at leastare made to be closer in pressure, by employing a vacuum in the topchamber;

FIG. 2 is a cross-sectional view of a prior art magnetron sputteringsystem wherein the target and magnetron assemblies are provided withheat exchange channels to cool the target. The magnetron sputteringsystem also generates a low pressure region in the magnetron assemblysuch that the backing plate sees a pressure differential much lower thanatmospheric pressure;

FIG. 3 is a detailed cross-sectional view of a first embodiment of atarget assembly and magnetron assembly according to the presentinvention taken parallel to the motion of the magnetron;

FIG. 4 is a detailed cross-sectional view of the embodiment shown inFIG. 3 taken perpendicular to the motion of the magnetron;

FIGS. 5A and 5B are top and cross-sectional views of a backing plateaccording to the embodiment shown in FIG. 3;

FIGS. 6A, 6B, and 6C are top, cross-sectional, and bottom views of aheat exchanger/pressure relief plate according to the embodiment shownin FIG. 3;

FIGS. 7A, 7B, and 7C are top, cross-sectional, and bottom views of aninsulation cover according to the embodiment shown in FIG. 3;

FIGS. 8A and 8B are top and cross-sectional views of an insulator sleeveaccording to the embodiment shown in FIG. 3;

FIG. 9 is a detailed cross-sectional view of a cooling fluidinlet/outlet port of a target assembly according to the embodiment shownin FIG. 3;

FIG. 10 is a detailed cross-sectional view of a rough vacuum portconnecting to the internal passages of a target assembly according tothe embodiment shown in FIG. 3;

FIG. 11 is a perspective view of a second side of the heatexchanger/pressure relief plate of FIGS. 6A-6C;

FIG. 12 is a perspective view of a first side of the heatexchanger/pressure relief plate of FIGS. 6A-6C;

FIG. 13 is a schematic side cross-sectional view of the embodiment shownin FIG. 3;

FIG. 14 is a schematic side cross-sectional view of a second embodimentof the present invention, wherein a side of the target backing plateprovides fins and heat exchange fluid cavities and a side of aninsulation cover provides fins and vacuum cavities;

FIG. 15 is a schematic side cross-sectional view of a third embodimentof the present invention which employs heat exchange fluid channelsdrilled through the heat exchanger/pressure relief plate and a side ofan insulation cover provides fins and cavities;

FIG. 16 is a schematic side cross-sectional view of a fourth embodimentof the present invention that employs heat exchange fluid channelsdrilled through the target backing plate;

FIG. 17 is a schematic side cross-sectional view of a fifth embodimentof the present invention that employs a monolithic target/target backingplate.

FIG. 18 is a schematic side cross-sectional view of a magnetronapparatus employing the target assembly and magnetron assembly of FIG. 3taken parallel to the motion of the magnetron.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The new configuration for a high productivity sputtering device, byproviding a target or cathode assembly including a thin integral coolingand pressure relief structure, includes a sputtering process chamberhaving a top peripheral flange surface. A target assembly is supportedon the flange. The target assembly includes a target, a backing plate, aheat exchanger/pressure relieving plate, as well as an insulation cover;all in one integral assembly.

In a monolithic configuration the target (e.g., material to be consumed)and target backing plate can be a single piece of material; an O-ringgroove (for sealing against the main insulator resting on the processchamber) and other features are machined into it. In other instances thetarget material is separate from the target backing plate and is joinedwith the target backing plate using commonly known joining techniquessuch as soldering.

The heat exchanger/pressure relief plate, with cavities or groovesmachined or formed on both sides therein, is firmly attached to thetarget backing plate; this side of the heat exchanger/pressure relievingplate which is in intimate contact with the backing plate serves as aheat exchanger by providing a path for cooling fluid in which to flow.The other side of the heat exchanger/pressure relief plate is inintimate contact with an insulation cover to form a vacuumpressure-relieving chamber with the process chamber by providing a pathto rough vacuum which is shared with the process chamber or may beindependently pumped but pressure synchronized with the process chambervacuum state.

The vacuum forces exerted on the target assembly by the process chamberare reduced substantially and nearly equally by the vacuum forcesexerted on the pressure relieving passage (pressure relieving chamber )formed by the heat exchanger/pressure relieving plate with theinsulation cover. Typically, the pressure relieving chamber is apressure equalizing chamber.

The cavities or grooves have intermediate fins or walls that helpmaintain the dimensions of both the cooling and the pressure relievingpassages over the wide span of the heat exchanger/pressure relievingplate. The fins or walls prevent the pressure in either the cooling orthe pressure relieving passages to cause significant deflections of theheat exchanger/pressure relieving plate, or the target and its targetbacking plate, or the insulation cover. Of course the fins and walls canbe arranged in a wide variety of configurations and shapes, e.g.,spiral, radial, “v” type layouts and so on.

For ease of, fabrication, the heat exchanger/pressure relieving plate ismachined from 6061-T6 aluminum alloy plate that may be anodized forimproved corrosion resistance, except in the area where the powercontact is attached.

The heat exchanger/pressure equalizing plate must be tightly joined tothe back of the target backing plate so that a tight seal is created forthe cooling fluid. The cooling fluid cavities or grooves are configuredin such a way so as to distribute the cooling liquid flow over asubstantial area of the target backing plate; thereby, providing amaximum cooling or heating effect over the whole target at a generallyuniform rate.

The heat exchanger/pressure equalizing plate can be joined to the targetbacking plate by any reliable means. However, it has been found thatO-ring seals secured with standard fasteners (preferably non-magnetic)are highly reliable and cost effective means to join the heatexchanger/pressure equalizing plate to the target backing plate, andstill maintain a highly reliable seal for the cooling liquid to flow.

Likewise, the insulation cover unit is tightly joined to the heatexchanger/pressure relieving plate using O-ring seals and standard nylonfasteners in order to maintain the insulation integrity of theinsulation cover. The insulation cover is electrically isolated from theenergized sputtering target. Typically, this is achieved by having theinsulation cover made entirely of insulating material and/orelectrically insulated from the energized sputtering target. Theinsulation cover unit may be a plate or have another appropriate shape.

In another embodiment, the cooling fluid passages and grooves areinstead machined on the target backing plate. Likewise, vacuum passagesand grooves can be machined on the insulation cover. Therefore, the heatexchanger/pressure relieving plate can be manufactured as a flatsheet-metal piece secured between the backing plate and insulationcover. However, for example, when solder bonding, a non-grooved backingplate is generally preferred, in particular for ease of inspecting thesolder-bonded joint.

The full target assembly is comprised of a target, backing plate, heatexchanger/pressure relieving plate, insulation cover, cooling fluid andvacuum lines, and male (non-energized end) cathode-power contact. Thetarget assembly, fully assembled, is placed over the main insulatorresting on the sputtering process chamber.

The electrically charged target assembly is isolated from the sputteringprocess chamber by resting over the main insulator which is normallymade of a ceramic material such as fired alumina (99.5% Al₂O₃.). Thealumina main insulator provides a high dielectric-strength,non-flammable, non-permeable insulation that can maintain dimensionalstability under the high loads exerted by vacuum in the process chamber.

In addition, the perimeter of the target assembly is isolated fromoperator contact by an insulating sleeve that extends from theinsulation cover into the perimeter of the process chamber. Theinsulating sleeve can be constructed in sections that are machined fromphenolic bar-stock. The sections may be bonded together using tongue andgroove joints for added strength, and if desired, precise positioning ofthe sections can be accomplished by machining mating holes at the jointand positioning the sections using close-tolerance phenolic dowel pinsfor alignment. Of course, a monolithic insulating sleeve can be formedby manufacturing processes such as casting or machining from platestock.

To cool or heat the target assembly, high resistivity water is normallyused so that there is negligible current loss through the coolingpassages while the target assembly is being energized. A pair ofgrounded inlet/outlet insulated hose assemblies are connected tohydraulic fitting ports machined into the top corners of the insulationcover. The hydraulic fitting ports are in communication with matingopenings (seams of the openings sealed by O-rings) to the coolingpassages formed between the heat exchanger/pressure relieving plate andthe backing plate, the inlet/outlet insulated hoses provide amplecooling/heating fluid to the backing plate.

The insulation cover is machined preferably of phenolic for its highmechanical and dielectric strength properties, but other insulationmaterials, for example, DELRIN (E. I. Du Pont de Nemours and Co. Corp.,Wilmington, Del.) or polycarbonate may also be used.

In addition, one or more vacuum-fitting ports are machined into theinsulation cover to provide one or more passages for vacuum in the spaceformed between the heat exchanger/pressure relieving plate and theinsulation cover.

Once the target assembly is placed over the process chamber, and whilewaiting for proper vacuum levels to be reached, the magnet enclosingchamber may be positioned over the target assembly in preparation forsputtering. The magnet enclosing chamber, once positioned over thetarget assembly, places the magnetron near the top of the insulationcover (of the target assembly), at a short distance from the consumablesurface of the target. In addition, the power supply connection is made;that is, the female contact (energized-end or end that connects to thepower supply, DC or RF generator) mounted in the magnet enclosingchamber mates with the male cathode-power contact mounted on the targetassembly. However, the enclosing magnet chamber may be removed at anytime from the assembly without affecting the vacuum components or vacuumintegrity of the processing chamber.

In the present configuration, a magnet sweeping mechanism placed in themagnet chamber can be adjusted to optimize the distance between themagnetron and the surface of the target; thereby, improving the targeterosion pattern; and consequently, the film characteristics on thesubstrate. If desired, the magnetron comprises a permanent magnet array,that has a very strong magnetic field, and is very narrow (narrowturn-around region) that produces a “cigar-like” plasma field.

Since permanent magnets reduce their magnetic strength at elevatedtemperatures, the magnet chamber may be fitted with forced-air coolingto keep the magnetron at nearly ambient temperature while sputtering;thereby preserving the permanent magnet's magnetic strength, andallowing the magnetron to operate at very high deposition rates.

In the present configuration as described, very large-area substratesare uniformly coated using targets slightly larger than the substrates.The design uses the accepted design rule that the target overhang byabout 2.0″ in any direction over the substrate; however, for improvedfilm thickness uniformity, larger area targets are used, but at theexpense of increased costs.

Further, it is generally accepted that electron flow at the turn-aroundregions of a sweeping magnetron vary at the end of travel (decelerating,stopped, and accelerating towards the other end of the scan while inclose proximity to the broad-side of the anode or dark-space shield);therefore, the plasma intensity at one end of the magnetron varies fromthe other end of the magnetron. This difference in plasma intensitycauses one comer of the target to erode differently from the other.

In the present configuration, in order to maintain uniformity ofdeposition throughout the useful life of the target, the magnetrondistance to the target surface is adjusted periodically by adjusting oneor more of the springs height mounted on the magnetron-lift base plate.Similarly, to compensate for electron-flow effects at the end of travel,the inclination of the magnetron with respect to the direction of travelis adjusted by rotating the slide shafts supporting the magnetron, thatis, adjusting the parallelism of the slide shafts with respect to thedirection of motion.

Typical techniques to practice magnetron sputtering suitable for usewith cathodes according to the present invention include dc sputtering,rf sputtering, microwave sputtering, or other suitable frequencytechniques. Such methods are disclosed by U.S. patent application Ser.No. 09/559,600, filed Apr. 28, 2000, U.S. patent application Ser. No.09/671,681, filed Sep. 28, 2000, and U.S. provisional patent applicationSer. No. 60/235,913, filed Sep. 28, 2000, all of which are incorporatedherein by reference in their entirety.

An optional goal of the present invention is to provide cathodes toassist in achieving directional PVD and/or IPVD without a secondary,post emission ionization stage beyond that ionization produced by thecathode.

Target Materials

The present thin target assembly benefits sputtering targets generally.Some targets may include strong crystallographically textured, highlyuniform (across its area and through target thickness) polycrystallinetarget materials and/or single crystal sputtering targets (which may beone piece or mosaic structures comprised of several pieces of singlecrystal of one or a mixture of crystallographic orientations) in amanner to produce a highly directional emitted sputtered particle fluxfrom a scanning magnetron sputtering device. Note, the degree of textureis generally defined herein through the Multiple of a RandomDistribution (MRD) (or density). The MRD being determined by X-raydiffraction (XRD) pole figure measurement. The MRD compares anorientation density with that of a sample with no preferred orientation(uniform distribution). Other simpler descriptions relate the intensityof the diffraction signal from a given orientation in terms of relativeintensity (ratio) with respect to diffraction from other specified peaksor a specific peak in the XRD spectrum.

The sputter targets may be made by a variety of techniques, for exampledirectional solidification techniques, seed techniques, orElectrochemical Deposition Techniques (EDT).

It would be desirable to make commercial size targets by a seedtechnique which may be a variation of a directional solidificationtechnique described below, without or with a seed crystal, or avariation of a Bridgeman technique, Czochralski technique, orrecrystallization technique, or other techniques.

Seeded techniques utilizing directional solidification of materials canproduce sputtering targets with predetermined crystallographicorientation. At least three techniques can provide a predetermninedtexture. These methods include: Gradient Freeze, Bridgman andCzochralski.

The Gradient Freeze method imposes a controlled temperature gradient todirectionally solidify the liquid metal in either single crystalorientation or in a multi grained columnar structure with predeterminedorientation.

The Bridgeman technique uses a fixed temperature gradient as supplied bya multi zoned furnace with induction, resistance, radiant, plasma orelectron beam as the heating source. The solidification interfacevelocity and profile is controlled by the relative motion between thematerial and furnace. The method includes stationary furnace elementswith moving crucibles or stationary crucibles with moving furnaceelements.

In the Czochralski technique a rotating seed of predeterminedorientation is dipped in a liquid bath of the growth material, and thenslowly withdrawn. The temperature of the molten bath is held close tothe material's melting point to ensure that the seed does not dissolveinto the bath. During withdrawal, crystalline material solidifies on theend of seed in the same orientation as the seed. The liquid bath is keptmolten with the use of induction, resistance, radiant, plasma orelectron beam as the heat source.

An embodiment of the directional solidification technique employs aVacuum Induction Melter (VIM) that utilizes two sets of heating elements(coils) and Thermocouples (T/Cs) stacked vertically to heat a crucibleand melt the material for the target. The temperature is monitored withthese two T/Cs and a Pyrometer. The material undergoes a melting phasein which both sets of heating coils are used and a cooling phase duringwhich only the top set is used. This forces the crucible and targetmaterial, e.g., Copper, to cool from the bottom ideally allowing onelarge grain to grow, although typically a few large grains can form.

Directional solidification samples may be sawed to expose suitablyorientated sections of crystal.

The Electrochemical Deposition Technique (EDT) endeavors to electro-forma columnar, crystallographically orientated deposition structure basedaround this process.

Generally for directional emission, a single crystal or apolycrystalline material in which there is a dominant certain texture ora suitably engineered polytextured material in which certain texturalcomponents having desired emission components are combined anddistributed in appropriately controlled volume fractions to produce adesired emission spectrum is preferred.

Single crystal emission can be conal, or approximate to conal, e.g., inCu (110) and (111) systems. That is, emission directionality can beachieved in two dimensions. When considering deposition usingpolycrystalline targets, other target attributes such as grain size andgrain size distribution may be important.

Surface Conditions

Sputter emission is a near surface effect. Most emission occurs fromdepths within a few atomic layers from the surface. The condition of thetarget surface therefore strongly affects the angular distribution ofas-emitted sputtered particles for both single crystal andpolycrystalline targets. The initial surface crystallographic textureand topology, presence of surface defects, such damage including thatinduced during fabrication, for example strain effects and/orcontamination, e.g., foreign material, oxides etc. of the sputteringtarget prior to sputtering are factors that may affect the emittedangular distribution (EAD) and directionality. Also, the target'ssurface topology, texture and/or surface damage produced by particleirradiation developed through the sputtering process (related to powerapplied to sputter the target, sputtering gas species and other processvariables), backsputtered particles and sputter generated contaminantfilms, etc., are factors that may affect the emitted angulardistribution (EAD) and directionality.

Generally, polycrystalline commercial targets have a high qualitycommercial no. 16-32 machined finish prior to sputtering. Singlecrystals typically have a diamond turned mirror finish or chemo, orchemomechanical surface preparation. Sputter conditioning can then beapplied, if required, to establish directional emission in suitabletarget materials through removal of surface contamination, damage, etc.,and to establish a directionally emitting surface layer. The extent andability of sputter conditioning required to produce such directionalemission is dependent on the nature of the surface preparation. Sputterconditioning occurs as soon as the target is exposed to the sputteringparticle flux. Highly polished, low damage surfaces, e.g., diamondturned surfaces may not require any intentional sputter pre-conditioningor less conditioning than relatively rough, damaged machine finishedsurfaces.

Maintaining Directionality

From basic considerations at a macroscale, in magnetron sputtering thedynamic development of the sputtered surface topology into a macroscaleracetrack groove, through non-uniform sputter erosion, alters theeffective angles of incidence of the incident sputtering particles atthe target surface. A dynamically changing microtopology is alwaysproduced during sputtering, even on the surfaces of highly polishedsingle crystals; and given large differences in sputter rate typicallyexist over the racetrack cross section. However, it is possible tomaintain the intrinsic directional flux from single crystal or highlycrystallographically textured polycrystalline targets.

The macroracetrack groove is a consequence of the cross-sectionallyvarying sputter rate across the racetrack induced by the non-uniformracetrack plasma density produced in typical magnetron crossed electricand magnetic fields. Superimposed over the macroracetrack groove andother macrotopological features, e.g., machining grooves in the earlystages of target use, develops a fine scale, dynamic, steady state,“natural” sputter topology. “Natural” sputter topologies are complex.Generally, once a “steady state” is reached, they are characterized inmetallic target systems by low angle reliefs, i.e., features whichgenerally exhibit angles of less than 30 degrees with respect to thehypothetical surface plane of the target. Differences in height betweenfeatures in the “steady state” “natural” surface topology are estimatedto be less than about 100, generally less than about 50, or typicallyless than about 30, microns. In other words, the localized differencebetween the height of a peak and its adjacent valley or plain is lessthan about 100, about 50 or about 30 microns. Of course, the absolutedifference in height between the highest and lowest feature of thetarget may be over 100 microns, as for example where the target has anoverall curved shape. This is intended as a guide rather than a completedescription of these phenomena. The natural topology employed with thepresent invention is that which can be maintained at steady state acrossthe target during sputtering over an extended useful period.

The target surface topology is dynamic during sputtering. Complexerosion mechanisms can allow a dynamic equilibrium, or steady state tobe established. For example, the hills and valleys of the topology caneffectively erode at differential rates to keep the differences inheight between surface features below a predetermined tolerance. This isachieved by employing an overall erosion rate less than that whichoverwhelms the differences in erosion rates associated with thedifferent heights of surface features in the “natural” topology. As aresult, this topology can be maintained in a steady state duringsputtering, due to an overall steady erosion, for an extended period oftime, e.g., at least 30 minutes, at least one hour, or at least twohours. In contrast, if an overly fast erosion rate is selected and/or aracetrack plasma is applied statically for sufficient duration, thetarget would decay to an unsuitable macroracetrack scale topologyinduced by the cross-sectionally varying sputter bombardment rateresulting from the racetrack plasma density profile.

For highly uniform, crystallographically textured, directionallyemitting target materials generally the as emitted sputtered particleflux angular distribution (EAD) is not significantly affected by theshape, i.e., intensity distribution or the particle energy distribution(typically <1000 eV), of the incident sputtering ion flux profile inmagnetron sputtering. Rather, only the integrated intensity of theemitted flux profile across the racetrack, point to point, is affected,not the general shape of the emission distribution. Further, inspatially resolved emission experiments, emission is not necessarilycosine in nature. Small rotations of the EAD profile can occur. Theserotations are believed due to variation of the angle of incidence at thetarget of the sputtering particles. These can be minimized by suitablecathode operation, design of the magnetrons crossed magnetic-electricfield and sputter gas selection.

Further, controlled directional emitted particle flux of such materialscan be maintained over an acceptable power density applied to the targetuntil sufficient damage or topological disruption away from theabove-described “natural topology” produced by the sputtering ionsdisrupts the target surface and near surface sufficiently to degrade thedirectional emission condition. Similarly, e.g., a high degree ofbacksputtering or development of coarse sputtered surface topology candegrade the directional emission effect. Generally for suitably texturedtargets, directional emission can be observed after a short or evennegligible sputter bum-in period for a variety of carefully applied,surface finishes, e.g., diamond turned, chemically etched, polished(mechanically, chemomechanically, electrochemically) or carefullymachined targets.

Initial Surface Condition

Another factor to consider is initial surface condition. Due to thesurface nature of the sputter effect, initial surface condition isimportant. It can be the case, for a poorly prepared initial surface ona directional target material, that directionality may not be inducedeven after prolonged sputtering. There appears to be a thresholdtolerance for surface condition that is difficult to overcome even byprolonged sputter erosion, as the act of sputter erosion itself can thentend to perpetuate a non-directional surface condition. Generally,initial surface finish should be better or close to the dimensions ofthe “natural” surface topology as described above at least wheredirectional emission is desired.

For example, the pre-sputtering surfaces of typical “machined” targetsmay have a grooved finish close to the topographical dimensionality ofthe “natural” surface topology. Machined grooves may be typically lessthan 20 microns deep, approximately 100 microns wide, forming angles of˜20 degree to the surface plane. “Polished” targets may typically have apre-sputtered mirror finish to better than 1 micron. Similarly “diamondturned” surfaces may typically have a pre-sputtered mirror finish tobetter than 0.04 micron.

Magnetron Cathode (Magnet and Target) Design

FIG. 3 depicts a detailed cross-sectional view of an embodimentaccording to the present invention taken parallel to the motion of themagnetron 145. A sputtering apparatus 100 comprises primarily asputtering process chamber 101, a target assembly 154, and a magnetronassembly 124. The sputtering process chamber has a top flange 102, theflange has a shape and perimeter according to a predetermined substratesize; that is, a cylindrical flange is generally designed for anapparatus processing round-shape substrates such as silicon wafers usedin semiconductor fabrication; similarly, a rectangular flange isgenerally designed for an apparatus processing rectangular-shapesubstrates such as glass sheets used in flat-panel display fabrication.

The target assembly 154 is positioned over a main insulator 109,preferably made of ceramic material, and seals to it using an O-ring(not shown, e.g. VITON) inserted into O-ring groove 118 that is machinedinto the target backing plate 105 within target assembly 154. The maininsulator 109, positioned over the process chamber flange 102, insulatesthe energized target assembly 154 from the sputtering process chamber101. The main insulator 109 seals against process chamber flange 102using an O-ring (not shown, e.g. VITON synthetic rubber E. I. Du Pont deNemours & Co. Corp., Wilmington, Del.) inserted into O-ring groove 117machined into the top of flange 102 of process chamber 101. Therefore,in the above-described manner, the target backing plate 105, of targetassembly 154, covers the sputtering opening of sputtering processchamber 101 and seals the opening.

The target assembly 154 includes a sputtering target (“target”) 104,previously mentioned target backing plate 105, a heat exchanger/pressurerelieving plate 106, and insulation cover 110; each of the abovementioned components having first and second sides, the first and secondsides being opposite from one another.

A first side of sputtering target 104 is consumed by the sputteringaction in sputtering process chamber 101. A removable dark space shield103, extending into the opening of process chamber 101, surrounds theperimeter of sputtering target 104 and prevents sputtering beyond theedges of the first side of sputtering target 104. Dark space shield 103forms part of the anode, and is positioned a short distance (generallybetween 0.060″ to 0.125″) away from both the sputtering target 104 andtarget backing plate 105. Dark space shield 103 is secured to theprocess chamber 101 by brackets 112 and vented machine screws(preferably non-magnetic.) Brackets 112 mount over a mating recessmachined on the top of flange 102, vacuum side of the process chamber.

A second side of sputtering target 104 is in intimate contact to a firstside of target backing plate 105; the two components may be joined byany conventional manufacturing method such as bonded with Indium solder;however, the target 104 and target backing plate 105 can be monolithic.

A second side of target backing plate 105 is in intimate contact with afirst side of heat exchanger/pressure relieving plate 106. Cavities andfins machined in the first side of heat exchanger/pressure relievingplate 106 form, together with target backing plate 105, heating/coolingfluid passages 107 defined by fins 107A (FIG. 13). One or more inlet andoutlet heating/cooling fluid openings 170, 171 are machined near thecorners of heat exchanger/pressure relieving plate 106 to communicatewith inlet and outlet heating/cooling hydraulic fittings 114, 115. Theseam between the two plates is sealed by an O-ring (not shown, e.g.Buna) inserted into O-ring groove 119 machined into first side of heatexchanger/pressure relieving plate 106. The two plates are tightlysecured using standard machine screws fasteners 123 (preferablynon-magnetic.) Inlet and outlet heating/cooling fluid openings and holesfor fasteners (not shown) in communication with the heating/coolingfluid passages are sealed using concentrically mounted O-rings (notshown, e.g. Buna) with the openings and holes.

A second side of the heat exchanger/pressure relieving plate 106 is inintimate contact to a first side of the insulation cover 110. Cavitiesand fins machined in the second side of the heat exchanger/pressurerelieving plate 106 form, together with insulation cover 110,pressure-relieving passages 108 designed to communicate with roughvacuum in sputtering process chamber 101. One or more vacuum ports aremachined on the edges of insulation cover 110 to insert vacuum fittings116. Vacuum communication with pressure-relieving passages 108 is madethrough drilled openings 111 in the insulation cover 110. The seambetween the two plates is sealed by an O-ring (not shown, e.g. VITON)inserted into O-ring groove 120 machined into the second side of theheat exchanger/pressure relieving plate 106. The two plates are tightlysecured using standard machine screws fasteners (preferablynon-magnetic.)

Heating/cooling hydraulic fittings 114, 115 are inserted into the secondside of insulation cover 110, and O-rings (not shown, e.g. Buna) sealthe ports.

Insulation sleeve 113 surrounds target assembly 154 and extends into theperimeter of process chamber flange 102. Fixed fasteners 122 secure theinsulation sleeve 113 to target assembly 154. Floating shoulder screwfasteners 121 secure the insulation sleeve 113 to the process chamberflange 102, and compensate for dimensional changes of the O-rings in thestack of parts once vacuum is made.

Process/deposition parameters such as magnetron electrical impedance,plasma intensity and uniformity, etc. can be controlled by adjusting theposition of the magnetron with respect to the target as the magnetronsweeps the target surface. Magnetron assembly 124 provides a movablemagnetron 145 secured by fasteners to base plate 149. At each end ofbase plate 149, a slide mount 147 (fitted with Permaglide® bearings) ismounted to receive slide shafts 134. The ends of slide shafts 134 aresecured by supports 143 mounted to a magnetron lift base plate 125.Magnetron lift base plate 125 presses against four relatively stiffsprings 126 placed at each of its comers. The springs 126 are compressedbetween magnetron lift base plate 125 and magnetron housing 153 bystandard bolt and nuts connections 130.

The magnetron 145 slides freely on the slide shafts 134, and very littletransverse load, due to the magnetron's weight, is transmitted toleadscrew 133; thereby, extending the life of the leadscrew. Inaddition, the magnetron is simply pushed/pulled axially by the motion ofthe leadscrew nut 146 driven by leadscrew 133.

Mounting supports 143 can be rotated slightly (as much as 45 degrees) tocause the magnetron 145 to travel slightly rotated from perpendicular tothe leadscrew axis. This adjustment has proved advantageous incompensating for plasma electron-flow effects at the end of travel; thatis, plasma effects as the plasma approaches the anode from broad side.

Nut mount 148 is firmly attached to leadscrew nut 146, and is fittedwith a pair of Permaglide® bearings so that shafts 135 firmly mountedabout the middle of base plate 149 can transmit the push/pull motion ofthe leadscrew 133 to the magnetron 145; in this manner, the magnetron145 can also slide transversally to the axis of the leadscrew 133 whichis the required motion for adjusting the distance between the magnetron145 and the surface of target 104.

The distance between the magnetron 145 and the surface of target 104 iscontrolled by rotating a pair of cam shafts 132 using a pair ofself-locking worm 129 and worm gear 128 set. It is advantageous to use aworm and worm gear set because of their self-locking property; that is,a worm gear can not drive the worm. The ends of cam shafts 132 aresupported by mounts 150. Mounts 150 and shims 127 are firmly fastened tomagnetron housing 153. Shims 127 may be used to control the parallelismof the magnetron with respect to the surface of the target 104, andcompensate for manufacturing tolerances.

Cam shafts 132 contain a pair of cams 144 pressing against magnetronlift base plate 125; as the cams 144 rotate, it forces the magnetronlift base plate 125 to move crosswise to the axis of the cam shafts 132.Therefore, as the cams 144 rotate, the magnetron 145, sliding on slideshafts 134 that are mounted to supports 143 which mount to magnetronlift base plate 125, is also forced to move crosswise along with themagnetron lift base plate 125. This crosswise motion sets the distancebetween the magnetron 145 and the surface of target 104.

The leadscrew 133 is supported at one end by an axial angular contactball bearing which is fitted inside housing 142, and at the other end bya radial ball bearing fitted inside housing 151. Housings 142, 151 arefastened to magnetron housing 153 to firmly retain the leadscrew 133 init. Collar clamps 141 keep the axial angular contact ball bearingpreloaded for improved leadscrew positional accuracy. Covers 152 (motorside not shown) protect personnel from coming in contact with movingparts that protrude from the magnetron housing 153.

As shown, the end of leadscrew 133 that is closest to housing 142 (axialangular contact ball bearing end) receives a driven pulley 138 retainedto the leadscrew by a two-way shaft collar 140. Similarly, the shaft ofservomotor 131 receives driver pulley 136 retained by two-way collar139. The back and forth rotating motion of the servomotor 131 istransmitted to the leadscrew 133 by timing belt 137. If desired, anysuitable motor can be used for this purpose.

FIG. 4 is a detailed cross-sectional view of the embodiment shown inFIG. 3 taken perpendicular to the motion of the magnetron. The figureshows countersink fasteners 157 (preferably non-magnetic) securing theheating/cooling passages of target assembly 154 by pressing the heatexchanger/pressure relieving plate 106 against the target backing plate105. O-rings (not shown, e.g. Buna) inserted into machined O-ringgrooves 158 in the heat exchanger/pressure relieving plate 106, seal theholes for fasteners 157. Each O-ring groove 158 is machinedconcentrically with its corresponding hole for fasteners 157.

FIGS. 5A and 5B are top and cross-sectional views of a backing plate105. FIG. 5B shows a first side 159, and second side 160 of backingplate 105. The area on the first side 159 of backing plate 105 that isenclosed by O-ring groove 118 receives target 104. The second side 160of backing plate 105 receives heat exchanger/pressure relieving plate106.

The heat exchanger/pressure relieving plate 106 is firmly secured tobacking plate 105, within the area of heating/cooling fluid passages107, by means of countersink fasteners 157 (preferably non-magnetic.)The fasteners 157 are retained by blind tapped holes 162 machined intothe second side 160 of backing plate 105. In addition, through tappedholes 161 are also machined from the second side 160 of backing plate105. Through tapped holes 161 retain fasteners 123 and a male(non-energized end) cathodepower contact. The fasteners 123 firmlysecure the seam between heat exchanger/pressure relieving plate 106 andbacking plate 105.

FIGS. 6A, 6B, and 6C are top, cross-sectional, and bottom views of aheat exchanger/pressure relieving plate 106. FIG. 6A shows the cavitiesand fins within heating/cooling passages 107 of heat exchanger/pressurerelieving plate 106, and inlet and outlet coolant openings 170, 171communicating with heating/cooling passages 107. FIG. 6B, across-sectional view, shows first and second sides 172, 173 of heatexchanger/pressure relieving plate 106. FIG. 6C shows machined O-ringgrooves 174 that seal the seams of inlet and outlet coolant openings170, 171 between heat exchanger/pressure relieving plate 106 andinsulation cover 110.

FIGS. 7A, 7B, and 7C are top, cross-sectional, and bottom views of aninsulation cover 110. FIG. 7A shows a first side 181 of insulation cover110, and inlet and outlet coolant openings 170, 171. FIG. 7B, across-sectional view taken from FIG. 7A, shows machined ports 180 thatretain inlet and outlet heating/cooling hydraulic fittings 114, 115.Ports 180 are machined concentrically with inlet and outlet coolantopenings 170, 171, and from the second side 183 of insulation cover 110.FIG. 7C shows an opening 185 for a male (non-energized end)cathode-power contact that screws into the backing plate 105.

FIGS. 8A and 8B are top and cross-sectional views of an insulator sleeve113 according to the embodiment shown in FIG. 3. In particular FIG. 8Bis the cross-sectional view of the insulator sleeve 113 along view8B—8B.

FIG. 9 is a detailed cross-sectional view of a cooling fluidinlet/outlet port of a target assembly according to the embodiment shownin FIG. 3. FIG. 9 shows the insulation cover 110, over the heatexchanger/pressure relieving plate 106 which in turn is over the targetbacking plate 105 and target 104. The target backing plate 105 has anO-ring groove 118. The first side of the heat exchanger/pressurerelieving plate 106 has an O-ring groove 119 and the second side of theheat exchanger/pressure relieving plate 106 has an O-ring groove 174 forsealing a seam of inlet and outlet coolant openings fed by hydraulicfittings 114, 115 respectively. The insulation cover 110 is also securedto the heat exchanger/pressure relieving plate 106 has an O-ring groove120 by fasteners 123.

FIG. 10 is an enlarged view of a portion of FIG. 3 showing a detailedcross-sectional view of one of the drilled openings 111 for the roughvacuum port 116 connecting to the internal passages of the targetassembly.

FIG. 11 is a bottom perspective view of the heat exchanger/pressurerelief plate of FIGS. 6A-6C, showing fins 175 and cavities.

FIG. 12 is a top perspective view of the heat exchanger/pressure reliefplate of FIGS. 6A-6C.

FIG. 13 shows a simplified schematic diagram of a side cross section ofthe first embodiment of the present invention taken along the transverseline 13—13 shown in FIG. 6A.

FIG. 14 shows a simplified schematic diagram of a side cross section ofa second embodiment of the present invention. This embodiment is thesame as the first embodiment except that, cooling fluid cavities 207 andfins 207A are provided on a side 272 of a target backing plate 205, andfins 275 and vacuum cavities between the fins 275 are provided on aninsulation cover 210. Therefore, the heat exchanger/pressure relievingplate 206 can be manufactured as a flat sheet-metal piece securedbetween the backing plate 205 and insulation cover 210. However, forexample, when solder bonding, a non-grooved backing plate is generallypreferred, in particular for ease of inspecting the solder-bonded joint.

FIG. 15 shows a simplified schematic diagram of a side cross section ofa third embodiment of the present invention. This embodiment is the sameas the first embodiment except that, cooling fluid cavities are providedas channels 307A drilled in respective straight paths completely througha heat exchanger/pressure relieving plate 306. An appropriate header orother feeding system (not shown) may be provided to feed and remove heatexchange fluid from these channels 307A. For example, the channels 307Amay have threaded ends for fittings to communicate with a heat exchangefluid feed system. Of course, rather than a straight path other channelpaths, e.g., curved or V-shapes, may be employed. Fins 375 are providedon a side 373 of the heat exchanger/pressure relieving plate 306 to,together with an insulation cover 310, define vacuum cavities. Also, thetarget backing plate 305 and target 304 are located below the heatexchanger/pressure relieving plate 306. Therefore, the heatexchanger/pressure relieving plate 306 can be secured between thebacking plate 305 and the insulation cover 310.

FIG. 16 shows a simplified schematic diagram of a side cross section ofa fourth embodiment of the present invention. This embodiment is thesame as the first embodiment except that, cooling fluid cavities areprovided as channels 407 drilled in respective straight paths completelythrough a target backing plate 405. An appropriate header or otherfeeding system (not shown) may be provided to feed and remove heatexchange fluid from these channels 407. Of course, rather than astraight path other channel paths, e.g., curved or V-shapes, may beemployed. Fins 475 are provided on a side 473 of the heatexchanger/pressure relieving plate 406 to, together with an insulationcover 410, define vacuum cavities. Also, the target backing plate 405and target 404 are located below the heat exchanger/pressure relievingplate 406. Therefore, the heat exchanger/pressure relieving plate 406can be secured between the backing plate 405 and the insulation cover410.

FIG. 17 shows a simplified schematic diagram of a transverse crosssection of a fifth embodiment of the present invention. This embodimentis the same as the first embodiment except that the target and targetbacking plate 505 is a single monolithic structure rather than a targetattached to a backing plate. Thus, cooling fluid cavities 507 and fins507A are provided on a side 572 of a heat exchanger/pressure relievingplate 506 and fins 575 are provided on an opposed side 573 of the heatexchanger/pressure relieving plate 506 to, together with an insulationcover 510, define vacuum cavities. The heat exchanger/pressure relievingplate 506 is located between the insulation cover 510 and the monolithictarget backing plate and target 505. Therefore, the heatexchanger/pressure relieving plate 506 can be secured between themonolithic target backing plate and target 505 and insulation cover 510.

FIG. 18 is a schematic side cross-sectional view of a sputteringapparatus 100 employing the target assembly 154 and magnetron assembly124 of FIG. 3. FIG. 18 also shows a substrate 98 that receives sputteredmaterial from the target 104. The substrate 98 is located in the processchamber 101 kept under vacuum drawn by a port 96 connected to a vacuummeans (not shown). The target assembly 154 seals an upper portion of theprocess chamber 101. The magnetron housing 153 is located above thetarget assembly 154. The magnetron housing 153 may be under vacuum or atambient pressure. The magnetron housing 153 may be clamped (by removableclamps) to the target assembly with an O-ring therebetween or bolted orother wise attached to be part of the sputtering apparatus. When themagnetron housing 153 is to operate at vacuum pressure, the magnetronhousing 153 is attached to the target assembly 154 to form a seal.However, when the magnetron housing 153 is to operate at ambientpressure, it is not necessary to attach the magnetron chamber to thetarget assembly 154 to form a seal. When the magnetron housing 153 is tooperate at ambient pressure, the magnetron housing 153 may be attachedto the target assembly 154 with or without forming a seal therebetween,or the magnetron housing 153 may simply be placed over the targetassembly 154.

While the invention has been described with regard to specificembodiments, those skilled in the art will recognize that changes can bemade in form and detail without departing from the spirit and scope ofthe invention. For example, the evaluations described here are merelyrepresentative of the invention and should not be considered to limitthe scope of the invention to the method or structure herein described.

We claim:
 1. A magnetron sputtering apparatus comprising: a housing, at least one magnetron within the housing; a substrate; a sputtering processing chamber having a top flange, the flange having a shape and perimeter according to a predetermined form, the substrate being within the sputtering process chamber; a sputtering target assembly sealed to and insulated from the flange, such that a vacuum is capable of being maintained in the sputtering process chamber; wherein the sputtering target assembly comprises: a sputtering target and target backing plate assembly having opposed first and second sides, the first side providing material for sputtering, a pressure relief plate having opposed first and second sides, the target and target backing plate assembly second side being in contact with the first side of the pressure relief plate, heat exchange passages selected from at least one member of the group consisting of: heat exchange passages defined between the opposed sides of the sputtering target and backing plate assembly, heat exchange passages defined between the opposed sides of the pressure relief plate, and heat exchange passages defined by heat exchange cavities formed in at least one member of the group consisting of the first side of the pressure relief plate and the second side of the target and target backing plate assembly, wherein the heat exchange passages are formed between the first side of the pressure relief plate and the second side of the target and target backing plate assembly which enclose the heat exchange cavities, the heat exchange passages having one or more inlet and outlet openings, an insulation cover unit having opposed first and second sides, wherein the insulation cover unit is electrically isolated from the sputtering target; wherein the second side of the pressure relief plate is in contact with the first side of the cover unit to form at least one vacuum pressure space therebetween capable of maintaining a vacuum therein and the at least one vacuum pressure space having at least one vacuum port; wherein the pressure in the sputtering processing chamber is vacuum pressure which is the same or different from the pressure in the at least one vacuum pressure space; wherein every magnetron of the magnetron sputtering apparatus is outside the at least one vacuum pressure space of the sputtering target assembly.
 2. The magnetron sputtering apparatus of claim 1, wherein the heat exchange passages are selected from at least one member of the group consisting of(a) (a) heat exchange passages defined within the sputtering target and backing plate assembly, (b) heat exchange passages defined by having heat exchange cavities formed in the first side of the pressure relief plate such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the pressure relief plate and the target and target backing plate assembly enclosing those heat exchange cavities, and (c) heat exchange passages defined by having heat exchange cavities formed in the second side of the target and target backing plate assembly such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the target and target backing plate assembly and the pressure relief plate enclosing those heat exchange cavities.
 3. The magnetron sputtering apparatus of claim 1, wherein the at least one vacuum pressure space is defined by vacuum passages capable of maintaining a vacuum and having at least one vacuum port, the vacuum passages selected from at least one member of the group consisting of: (a) vacuum passages defined by having vacuum cavities formed in the second side of the pressure relief plate such that, when the first side of the insulation cover unit is contacted to the second side of the pressure relief plate, the vacuum passages are formed between the vacuum cavities in the pressure relief plate and the insulation cover unit enclosing those vacuum cavities, and (b) vacuum passages defined by having vacuum cavities formed in the first side of the insulation cover unit such that, when the second side of the pressure relief plate is contacted to the first side of the insulation cover unit, the vacuum passages are formed between the vacuum cavities in the insulation cover unit and the pressure relief plate enclosing those vacuum cavities.
 4. The magnetron sputtering apparatus as in claim 1, wherein the heat exchange passages are defined within the sputtering target and target backing plate assembly to have channels having a perimeter, transverse to a direction for flow of heat exchange fluid, entirely defined by the sputtering target and target backing plate assembly.
 5. The magnetron sputtering apparatus as in claim 1, wherein the heat exchange passages are defined by having heat exchange cavities formed in the first side of the pressure relief plate such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the pressure relief plate and the target and target backing plate assembly enclosing those heat exchange cavities.
 6. The magnetron sputtering apparatus as in claim 5, wherein the second side of the target and target backing plate assembly is generally flat.
 7. The magnetron sputtering apparatus as in claim 1, wherein the heat exchange passages are defined by having heat exchange cavities formed in the second side of the target and target backing plate assembly such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the target and target backing plate assembly and the pressure relief plate enclosing those heat exchange cavities.
 8. The magnetron sputtering apparatus as in claim 7, wherein the first side of the pressure relief plate is generally flat.
 9. The magnetron sputtering apparatus as in claim 1, wherein the at least one vacuum pressure space comprises vacuum passages defined by having vacuum cavities formed in the second side of the pressure relief plate such that, when the first side of the insulation cover unit is contacted to the second side of the pressure relief plate, the vacuum passages are formed between the vacuum cavities in the pressure relief plate and the insulation cover unit enclosing those vacuum cavities.
 10. The magnetron sputtering apparatus as in claim 9, wherein the first side of the insulation cover unit is generally flat.
 11. The magnetron sputtering apparatus as in claim 1, wherein the at least one vacuum pressure space comprises vacuum passages defined by having vacuum cavities formed in the first side of the insulation cover unit such that, when the second side of the pressure relief plate is contacted to the first side of the insulation cover unit, the vacuum passages are formed between the vacuum cavities in the insulation cover unit and the pressure relief plate enclosing those vacuum cavities.
 12. The magnetron sputtering apparatus as in claim 11, wherein the second side of the pressure relief plate is generally flat.
 13. The magnetron sputtering apparatus of claim 1, wherein the sputtering target and target backing plate assembly comprises a sputtering target having opposed first and second sides and a target backing plate assembly having opposed first and second sides; the sputtering target second side is in contact with the first side of the target backing plate assembly; and the target backing plate assembly second side is in contact with the first side of the pressure relief plate.
 14. The magnetron sputtering apparatus as in claim 1, wherein the sputtering target and target backing plate assembly is a monolith of a material.
 15. The magnetron sputtering apparatus as in claim 1, wherein the target backing plate assembly is configured to cover a top opening of the sputtering process chamber to seal the top opening, and wherein a magnet of the magnetron operates at ambient pressure while maintaining a vacuum pressure in the at least one vacuum pressure space.
 16. The magnetron sputtering apparatus as in claim 1, wherein the housing comprises a top chamber in which the at least one magnetron is located, wherein the target backing plate assembly is configured to cover a bottom opening of the top chamber of the housing to seal the bottom, and such that a magnet of the at least one magnetron is capable of operating at ambient pressure while maintaining a vacuum pressure in the at least one vacuum pressure space.
 17. The magnetron sputtering apparatus as in claim 1, wherein the heat exchange passages run parallel to one another and are configured to distribute a fluid flow approximately equally between them when they receive the flow from an inlet manifold area.
 18. The magnetron sputtering apparatus as in claim 1, wherein the heat exchange passages run adjacent to one another and are configured to distribute a fluid flow to maintain a generally uniform temperature across a surface of the sputtering target and target backing plate assembly.
 19. The sputtering apparatus as in claim 1, wherein the sputtering target assembly is configured to cover a bottom opening of a top chamber to seal the bottom opening such that a vacuum chamber beneath the bottom opening is capable of operating at a vacuum pressure while the top chamber operates at ambient pressure, and while a vacuum pressure is maintained in the at least one vacuum pressure space, wherein the pressure in the vacuum chamber is the same or different from the pressure in the at least one vacuum pressure space.
 20. The sputtering apparatus as in claim 1, wherein the sputtering target assembly sealed to and insulated from the flange defines a vacuum passage to a vacuum system from the vacuum pressure space.
 21. A scanning magnetron sputtering apparatus comprising: a magnetron assembly comprising a movable magnetron; a magnetron housing comprising a top chamber for locating the magnetron therein and a sputtering process chamber for locating a substrate therein; a sputtering target assembly between the top chamber and the sputtering process chamber, comprising a target surface for providing sputtering material; the magnetron assembly comprising: the movable magnetron, a magnetron lift base plate mounted to the magnetron housing, springs compressed between the magnetron lift base plate and the magnetron housing, wherein the magnetron lift base plate presses against the springs, the magnetron being functionally attached to the magnetron lift base plate, and connected to a drive shaft to control motion of the magnetron; rotatable cam shafts mounted within the housing, and a gear for controlling rotation of the cam shafts to control distance between the magnetron and the target surface for providing sputtering material, wherein the cam shafts contain cams pressing against the magnetron lift base plate such that rotation of the cams moves the magnetron lift base plate transverse to a longitudinal axis of the cam shaft and the magnetron functionally mounted to the magnetron lift base plate is also forced to move transverse along with the magnetron lift base plate to set the distance between the magnetron and the surface of the target.
 22. A linear scanning magnetron sputtering apparatus comprising: a magnetron assembly comprising a movable magnetron; a magnetron housing comprising a top chamber for locating the magnetron therein and a process chamber for locating a substrate therein; a sputtering target assembly between the top chamber and the process chamber, comprising a target surface for providing sputtering material; the magnetron assembly comprising: the movable magnetron, a magnetron base plate secured to the moveable magnetron, at least one slide mount fitted with bearings attached to the magnetron base plate, and slide shafts, wherein the slide mount is mounted to receive the slide shafts, a magnetron lift base plate mounted to the magnetron housing, wherein the ends of the slide shafts are mounted to the magnetron lift base plate, wherein the magnetron slides freely on the slide shafts, springs compressed between the magnetron lift base plate and the magnetron housing, wherein the magnetron lift base plate presses against the springs, a leadscrew nut, a nut mount and a leadscrew having a longitudinal axis generally parallel to the slide shafts, the nut mount being attached to the leadscrew nut, and fitted with bearings so that shafts mounted about the base plate are capable of transmitting push/pull motion of the leadscrew; the magnetron being connected to the nut mount such that the magnetron is pushed or pulled axially by motion of the leadscrew nut driven by the leadscrew, the magnetron is also capable of sliding transversally to the axis of the leadscrew; rotatable cam shafts mounted within the housing, and a gear for controlling rotation of the cam shafts to control distance between the magnetron and the target surface for providing sputtering material, wherein the cam shafts contain cams pressing against magnetron lift base plate such that rotation of the cams forces the magnetron lift base plate to move transverse to a longitudinal axis of the cam shaft and the magnetron, sliding on slide shafts mounted to the magnetron lift base plate is also forced to move transverse along with the magnetron lift base plate to set the distance between the magnetron and the surface of the target.
 23. The linear scanning magnetron sputtering apparatus of claim 22, further comprising a first driver pulley attached to the leadscrew, a motor having a shaft attached to a second driver pulley, and a timing belt, wherein a back and forth rotating motion of the motor shaft is transmitted to the leadscrew by the timing belt.
 24. The linear scanning magnetron sputtering apparatus of claim 22, wherein the ends of the slide shafts are mounted to the magnetron lift base plate by being mounted to mounting supports mounted to the magnetron lift base plate, and the mounting supports are rotatable to cause the magnetron to travel rotated by an angle in the range of ±45 degrees from perpendicular to the leadscrew longitudinal axis.
 25. The linear scanning magnetron sputtering apparatus of claim 22, further comprising shims for controlling the parallelism of the magnetron with respect to the surface of the target, wherein ends of the cam are supported by cam shaft mounts, wherein the cam shaft mounts and shims are fastened to the magnetron housing.
 26. The linear scanning magnetron sputtering apparatus of claim 22, wherein the gear for controlling rotation comprises a respective self-locking worm and worm gear set provided for each cam shaft.
 27. A method of sputtering comprising: providing a sputtering target assembly comprising: a sputtering target and target backing plate assembly having opposed first and second sides, the first side providing material for sputtering, a pressure relief plate having opposed first and second sides, the target and target backing plate assembly second side being in contact with the first side of the pressure relief plate; heat exchange passages selected from at least one member of the group consisting of: heat exchange passages defined between the opposed sides of the sputtering target and backing plate assembly, heat exchange passages defined between the opposed sides of the pressure relief plate, and beat exchange passages defined by heat exchange cavities formed in at least one member of the group consisting of the first side of the pressure relief plate and the second side of the target and target backing plate assembly, wherein the heat exchange passages are formed between the first side of the pressure relief plate and the second side of the target and target backing plate assembly which enclose the heat exchange cavities, the heat exchange passages having one or more inlet and outlet openings; an insulation cover unit having opposed first and second sides; wherein the second side of the pressure relief plate is in contact with the first side of the insulation cover unit to form a vacuum pressure space therebetween and the vacuum pressure space has one or more vacuum ports, sputtering material from the target first surface; passing cooling medium through the heat exchange passages; and maintaining a vacuum in the vacuum pressure space.
 28. The method of claim 27, wherein the heat exchange passages are selected from at least one member of the group consisting of: (a) heat exchange passages defined within the sputtering target and backing plate assembly, (b) heat exchange passages defined by having heat exchange cavities formed in the first side of the pressure relief plate such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the pressure relief plate and the target and target backing plate assembly enclosing those heat exchange cavities, and (c) heat exchange passages defined by having heat exchange cavities formed in the second side of the target and target backing plate assembly such that, when the first side of the pressure relief plate is contacted to the second side of the target and target backing plate assembly, the heat exchange passages are formed between the heat exchange cavities in the target and target backing plate assembly and the pressure relief plate enclosing those heat exchange cavities.
 29. The method of claim 27, wherein the vacuum pressure space is defined by vacuum passages in which a vacuum is maintained, and the vacuum passages have one or more vacuum ports, the vacuum passages selected from at least one member of the group consisting of: (a) vacuum passages defined by having vacuum cavities formed in the second side of the pressure relief plate such that, when the first side of the insulation cover unit is contacted to the second side of the pressure relief plate, the vacuum passages are formed between the vacuum cavities in the pressure relief plate and the insulation cover unit enclosing those vacuum cavities, and (b) vacuum passages defined by having vacuum cavities formed in the first side of the insulation cover unit such that, when the second side of the pressure relief plate is contacted to the first side of the insulation cover unit, the vacuum passages are formed between the vacuum cavities in the insulation cover unit and the pressure relief plate enclosing those vacuum cavities.
 30. A sputtering apparatus configuration comprising: a sputtering process chamber, a target assembly, and a magnetron housing and a magnetron drive mechanism; the sputtering process chamber having a top flange, the flange having a shape and perimeter according to a predetermined form; the target assembly sealed to and insulated from the flange; wherein the target assembly comprises a sputtering target having opposed first and second sides, a target backing plate having opposed first and second sides, a heat exchanger/pressure relieving plate having opposed first and second sides, and an insulation cover unit having opposed first and second sides; wherein the first side of a sputtering target is for being consumed by sputtering action in the sputtering process chamber; wherein the second side of the sputtering target is in intimate contact to the first side of the target backing plate; wherein a set of cooling cavities and fins are disposed in the first side of the heat exchanger/pressure relieving plate; wherein the first side of the heat exchanger/pressure relieving plate is in intimate contact to the second side of the target backing plate; wherein another set of cavities and fins are disposed in the second side of the heat exchanger/pressure relieving plate; wherein the second side of the heat exchanger/pressure relieving plate is in intimate contact to the first side of the insulation cover unit to form a pressure relieving space.
 31. A sputtering apparatus assembly comprising: a sputtering process chamber, a target assembly, a magnetron, and a magnetron housing and a magnetron drive mechanism; the sputtering process chamber comprising a top flange, the flange having a shape and perimeter according to a predetermined form; the target assembly sealed to and insulated from the flange; the magnetron generally enclosed by the magnetron housing, and movable or scanable over the target assembly by the magnetron drive mechanism; wherein the target assembly comprises a sputtering target having first and second opposed sides, a target backing plate having first and second opposed sides, a heat exchanger/pressure relieving plate having first and second opposed sides, and an insulation cover unit having first and second opposed sides; wherein the magnetron is movable or scanable in close proximity to the second side of insulation cover, on the target assembly, using the magnetron drive mechanism; wherein the distance between the magnetron and the second side of insulation cover unit is adjustable throughout the useful life of the target without adversely affecting vacuum integrity in the sputtering process chamber. 